will
/ wouldThe graphic below shows how the modal verb
goes together with other auxiliary and main verbs, and it also shows the
approximate frequencyof
these combinations with " would". " would
" is the most frequent modal verb ( BNC
)

 "
will " is also very common, but it has
another written form ( -'ll) and a great
range of attitude and meaning depending on intonation and stress in speech.

GRAMMAR + VOCABULARY + CONTEXT = MEANING

"Context" includes the relationship between the speaker or listener,
writer or reader.

For example, there is a form called "future perfect" or "future
anterior" which is usually presented to learners as a " completed
action in the future", predicted by the speaker.
But...
 a medical expert, interviewed by a journalist about a recently
successful operation to separate conjoined twins said " It willhavebeen
a very difficult procedure".

 a press officer, talking about the latest photographs of a train
accident : " You willhave
seen the photos of the damage ..."

 a teacher, writing on a web page :" Most students of English
willhave
learned that "will" is "the
future form in English"

...these forms are frequent, a search of the BNC
with the term " will + have + vbn " will give examples of the
form with past, current and future references. They use "will
" to emphasise that they are giving an opinion about current and
past fact.

Most common uses are for  an offer:- " I'll help
you " / "I'llmake
some coffee"

 a promise or a threat. You decide which, depending
on the situation:- " I'll see
you tomorrow" / " I will always
love you" / " You will
never see me again" / " It willbe a cold day in hell before I help
you again!"

 negotiation:- " I'llpay
you an extra 3% if you candeliver
on Friday" / " For an extra 5% I'll deliver
it tomorrow"

 prediction- science/ astrology/ fortune telling:- "
There willbe rain
tomorrow in the west and north" / "Capricorns willhave a good year"

 a speaker's view of habit/liklihood:- "He'llbe at home in bed now" / " She'llbeworking all
next week"

 "-'ll"- relaxed future marker ( what is
any view of the future, if not an opinion?) Mixed in with any other prospective
language forms e.g. be + -ing , be going to , first form verbs which may
be independent of any modal. Find your own examples.

 restaurant/ shopping:- "I'llhave fish" / " I'lltake it"

 authority/announcement :- " The Court willrise" / " You will
not use your computer for playing games"
/ " The Queen will not visit
Margate this year"

It's wrong to ignore
the social and personal implications of these uses. And there canbe a crossover between the above areas. Check
with a search on the BNC
or with the COBUILD
corpus. As noted above, a search for any
of the modal perfect forms (a modal + have)
willthrow up
some interesting results, and that's a promise.